Abstract

The ionization/dissociation mechanism of cyclopentanone has been experimentally investigated in molecular beam by irradiating with intense 394 and laser fields with pulse duration of . The range of laser intensities varied from . For both wavelengths, the singly charged parent ion is observable while the doubly charged one cannot be found easily, although the fragmentation pattern supports its presence. Meanwhile, the extent of fragmentation at is less than that in the case. We quantitatively analyze the ionization processes of cyclopentanone in intense femtosecond laser by comparing the calculation results of ionization rate constants obtained from Ammosov-Delone-Krainov, Keldysh, and Keldysh-Faisal-Reiss (KFR) theories based on hydrogenlike atom model. We also compare the experimental and theoretical results; the generalized KFR theory is found to be useful in predicting the ionization yields of singly and doubly charged cyclopentanone ion. To interpret the dissociation patterns of the cyclopentanone ions, we have used the Rice-Ramsperger-Kassel-Marcus theory with the potential surfaces obtained from the ab initio quantum chemical calculations.

Received 25 June 2008Accepted 01 October 2008Published online 24 November 2008

Acknowledgments:

Support by the National Science Foundation of China (NSFC) under Grant Nos. 10534010 and 10374036 are acknowledged. A.M.M. thanks the US Department of Energy-Basic Energy Sciences (Grant No. DE-FG02-04ER15570) for partial support of this work.